Seven segment circuit for scoreboard

[sparky72]

seven segment digital scoreboard

Hi Ned; More questions. First of all let me tell you what I have done so far. I have completed the circuit for one pair of digits but when I push the counter switch the numbers start at 2 and go up in even numbers (2,4,6,8, etc) with no odd numbers. The reset switch works as it should setting the digits back to zero. Now comes the foolish question. Should the 1, 2, 3, 4, 5, 6, pins on the CD 4093 schmitt trigger debounce switch be connected, and if so where do the 3, and 4 pins go? The 1 & 2 along with 5 & 6 shows going to ground. I assumed these did not need to be connected as they did not seem to have anything to do with the circuit. Looking forward to hearing from you again with any suggestions you may have. Thanks again for your input. Lorne

 

[sparky72]

Hi Ned; More questions. First of all let me tell you what I have done so far. I have completed the circuit for one pair of digits but when I push the counter switch the numbers start at 2 and go up in even numbers (2,4,6,8, etc) with no odd numbers. The reset switch works as it should setting the digits back to zero. Now comes the foolish question. Should the 1, 2, 3, 4, 5, 6, pins on the CD 4093 schmitt trigger debounce switch be connected, and if so where do the 3, and 4 pins go? The 1 & 2 along with 5 & 6 shows going to ground. I assumed these did not need to be connected as they did not seem to have anything to do with the circuit. Looking forward to hearing from you again with any suggestions you may have. Thanks again for your input. Lorne

Good morning Ned;

Just checking to see if you have any suggestions to my latest query

 

[k7elp60]

Lorne,
Sorry for the delay in getting back to you. I think I made a mistake in that the counter advances on the negative going pulse. Try this, disconnect pin 11 of the 4093 from the 14553 counter. Connect pin 11 to pins 1&2 of the 4093. Connect pin 3 of the 4093 to the counter, this will invert the clock pulse. Connect only pins 5 & 6 of the 4093 to ground. All unused input pins of CMOS devices need to be either high or low.
Ned

 

[sparky72]

Lorne,
Sorry for the delay in getting back to you. I think I made a mistake in that the counter advances on the negative going pulse. Try this, disconnect pin 11 of the 4093 from the 14553 counter. Connect pin 11 to pins 1&2 of the 4093. Connect pin 3 of the 4093 to the counter, this will invert the clock pulse. Connect only pins 5 & 6 of the 4093 to ground. All unused input pins of CMOS devices need to be either high or low.
Ned

Thanks Ned, I will give that a try. No Problem for the delay as I was away for the weekend. I wasn't sure whether you had seen my post so I kinda bumped it up to the front again. I will get back and let you know one way or the other if I get it working. Lorne

 

[k7elp60]

Ned; You mentioned only pins 5&6 of the 4093 go to ground. Do I also have to disconnect pin 7 as it is going to ground as well?

No pin 7 is the common Vss pin for the 4093 and it has to be to ground in order for the rest of the gates to work properly.

 

[sparky72]

Seven segment led scoreboard

No pin 7 is the common Vss pin for the 4093 and it has to be to ground in order for the rest of the gates to work properly.

Good morning Ned; First of all let me tell you that half of the display is up and running great now, thanks to all the help that you gave me. As you probably know by now my electronic experience is just enough to get me into trouble, and I probably would not have been able to do it without the help of someone like you. For me it is a little late in the game to try and learn all the little intricacies of electronics as much as I would like to, but I try to do the best I can with what I know. This site is a great site, and very lucky to have dedicated and talented people like you as members, willing to share their information about electronics with anyone that needs it, especially for the younger generation as there is a wealth of information to be had and they are very lucky to have it. Anyway, thanks again for your patience and the help that you gave me. Now on to the second set of digits which should go a little easier for me. Since this is as much your project as it is mine I will let you know when I have completed it. Take care, Lorne

 

[sparky72]

Good morning Ned; First of all let me tell you that half of the display is up and running great now, thanks to all the help that you gave me. As you probably know by now my electronic experience is just enough to get me into trouble, and I probably would not have been able to do it without the help of someone like you. For me it is a little late in the game to try and learn all the little intricacies of electronics as much as I would like to, but I try to do the best I can with what I know. This site is a great site, and very lucky to have dedicated and talented people like you as members, willing to share their information about electronics with anyone that needs it, especially for the younger generation as there is a wealth of information to be had and they are very lucky to have it. Anyway, thanks again for your patience and the help that you gave me. Now on to the second set of digits which should go a little easier for me. Since this is as much your project as it is mine I will let you know when I have completed it. Take care, Lorne

Greetings Net; I am having a little problem with the second set of digits. I have it assembled now, using the same components as I used for the first. The only difference being is that I have used green clear leds. The display is all over the place when I activate the counter, even some segments being dimmer than others. Further checking made me realize that the Vf of the green leds is 2.1v The Vf of the red leds is 1.9. According to the formula for resistance to achieve 20ma per segment I should be using a 75 ohm resistor instead of 125 ohm that I used for the red leds. Would this discrepancy in the resistor ohms cause the display to be erratic? I have double checked and triple checked my circuit for any problems but to know avail. Looking forward to hearing from you again. Thank you.

 

[k7elp60]

Greetings Net; I am having a little problem with the second set of digits. I have it assembled now, using the same components as I used for the first. The only difference being is that I have used green clear leds. The display is all over the place when I activate the counter, even some segments being dimmer than others. Further checking made me realize that the Vf of the green leds is 2.1v The Vf of the red leds is 1.9. According to the formula for resistance to achieve 20ma per segment I should be using a 75 ohm resistor instead of 125 ohm that I used for the red leds. Would this discrepancy in the resistor ohms cause the display to be erratic? I have double checked and triple checked my circuit for any problems but to know avail. Looking forward to hearing from you again. Thank you.

Lorne,
I seriously doubt the values of the resistors will cause that problem unless there is a problem with the power supply.
Is the second set of digits independant from the first set of digits?
What are you using to power the whole system?
Ned

 

[sparky72]

Lorne,
I seriously doubt the values of the resistors will cause that problem unless there is a problem with the power supply.
Is the second set of digits independant from the first set of digits?
What are you using to power the whole system?
Ned

Yes the second set of digits are independent of the first. The circuit is a duplicate of the first with the exception of the led colour and the size of the wire that I used. For the first set I used telephone solid wire but I decided to buy some circuit wire from Radio Shack for the second as I found that the telephone wire was a little on the brittle side. The wire from Radio Shack is a little larger in dia. but not much. The power supply is a fully charged 12 volt battery. Lorne

 

[k7elp60]

Yes the second set of digits are independent of the first. The circuit is a duplicate of the first with the exception of the led colour and the size of the wire that I used. For the first set I used telephone solid wire but I decided to buy some circuit wire from Radio Shack for the second as I found that the telephone wire was a little on the brittle side. The wire from Radio Shack is a little larger in dia. but not much. The power supply is a fully charged 12 volt battery. Lorne

Lorne,
Possible problems are wiring errors or defective components. Here again with cmos IC's unused inputs have to be either tied to Vdd or ground. I have made wiring errors myself and could not immediately find them. Had some elso check my wiring or wait a while and recheck.
Ned

 

[sparky72]

Lorne,
Possible problems are wiring errors or defective components. Here again with cmos IC's unused inputs have to be either tied to Vdd or ground. I have made wiring errors myself and could not immediately find them. Had some elso check my wiring or wait a while and recheck.
Ned

Thanks Ned; You were right on. Further checking after I dug out the ULN2004 chip specs I realized that I had not grounded the # 8 pin. Every thing is working great now thanks to you. I have learned a great deal from you, doing this little project of mine. Thanks again. Take care, Lorne

 

[k7elp60]

Thanks Ned; You were right on. Further checking after I dug out the ULN2004 chip specs I realized that I had not grounded the # 8 pin. Every thing is working great now thanks to you. I have learned a great deal from you, doing this little project of mine. Thanks again. Take care, Lorne

Lorne,
I am glad I could help. I feel knowledge and experience is worthless unless one can pass it on to someone else. Just to give you a little of my background: I started in electronics as a young teenager about 12 or 13, and I will celebrate my 68th birthday this year. I remember before transistors and solid state. I have spent my whole life in electronics since I first started. I am avid experimenter and I am still building projects. I have been known to be somewhat stubbon and do things with electronics that goes against normal or conventional ways.
Cheers,
Ned

 

[sparky72]

Lorne,
I am glad I could help. I feel knowledge and experience is worthless unless one can pass it on to someone else. Just to give you a little of my background: I started in electronics as a young teenager about 12 or 13, and I will celebrate my 68th birthday this year. I remember before transistors and solid state. I have spent my whole life in electronics since I first started. I am avid experimenter and I am still building projects. I have been known to be somewhat stubbon and do things with electronics that goes against normal or conventional ways.
Cheers,
Ned

Ned; First of all let me say that the scoreboard is working very well with a couple of minor exceptions. Let's take one set of digits for instance. Let's use the number 01 for my example. All the segments on the 0 (a, b, c, d, e, & f,) are well lit, with g being totally off. However with the number 1 the b, & c, are well lit, but the a, d, e, f segments have a very faint glow to them. The g of the number 1 is totally off as it is with the number 0. This happens on any given number with both sets of digits on the score board. Another minor problem is that with the green set of numbers, when they are lit up, if you look close you can see the multiplexing at work. The multiplexing is not visible on the red set of digits. This is not a major problem, but I am just curious as to the reason. Lorne

 

[sparky72]

Seven Segment Scoreboard

Ned; First of all let me say that the scoreboard is working very well with a couple of minor exceptions. Let's take one set of digits for instance. Let's use the number 01 for my example. All the segments on the 0 (a, b, c, d, e, & f,) are well lit, with g being totally off. However with the number 1 the b, & c, are well lit, but the a, d, e, f segments have a very faint glow to them. The g of the number 1 is totally off as it is with the number 0. This happens on any given number with both sets of digits on the score board. Another minor problem is that with the green set of numbers, when they are lit up, if you look close you can see the multiplexing at work. The multiplexing is not visible on the red set of digits. This is not a major problem, but I am just curious as to the reason. Lorne

Good morning Ned. Do you have any suggestions for the above minor problem? Thanks again.

 

[k7elp60]

Lorne,
A couple of suggestions.
Adding a optical filter may help. I generally use a piece of transparent plexiglass the same color as the LED's to cover the readout surface of the displays. Although a lite smoke color works well also.
Increasing the size of the current limit resistors for the segment displays may help.
Finally changing the value of the capacitor on pins 3 & 4 of the 14553 counter IC to a lower value.
Ned